12/3/2020
WEEK 9
Java Library, JAVA API DOCS (java.lang, java.util,
Java Collection)
Java IO Stream & File IO
Materi pendukung lainnya: Wrapper, Type Casting,
Package, JAR, JAVADOC
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IKG2I4 – Software Project I
JAVA LIBRARY
Beberapa library utama:
– java.lang: Math (misalnya Math.PI, Math.SQRT)
– java.io: Input/Output
– java.util: Collection (struktur data yang sudah tersedia)
– Javax.swing: untuk membuat GUI Swing
– Javax.sql: untuk koneksi dan query ke database
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MATH
Contoh penggunaan Library Math:
import java.lang.Math;
class Utama{
public static void main(String args[]) {
System.out.println("E = " + Math.E);
System.out.println("PI = " + Math.PI);
double pi = Math.PI;
System.out.println("sin 90 = " + Math.sin(pi/2));
System.out.println("cos 90 = " + Math.cos(pi/2));
System.out.println("tan 90 = " + Math.tan(pi/2));
System.out.println("Konversi dari degree ke radian.......90 deg = " + Math.toRadians(90)
+ " rad.");
System.out.println("Konversi dari radian ke degree.......PI/2 rad = " +
Math.toDegrees(pi/2) + " deg.");
System.out.println("10 log 10000 = " + Math.log10(10000));
}
}
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IKG2I4 – Software Project I
MATH
Contoh penggunaan Library Math:
import java.lang.Math;
class Utama{
public static void main(String args[]){
int x = 800;
int y = 50;
System.out.println("max(x,y) = " + Math.max(x,y));
System.out.println("min(x,y) = " + Math.min(x,y));
double z = 5.6;
System.out.println("Pembulatan (round) dari z = " + Math.round(z));
System.out.println("Membangkitkan bilangan random antara 0 dan 1 = " + Math.random());
}
}
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IKG2I4 – Software Project I
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JAVA DATE
import java.util.Date;
class CobaDate {
public static void main(String args[]) {
System.out.println("Latihan menggunakan library class Date!");
Date tgl = new Date(2012,12,24);
Date tgl2 = new Date(2013,1,10);
System.out.println("Apakah tgl sebelum tgl2 ? " +
tgl.before(tgl2));
System.out.println("Apakah tgl setelah tgl2 ? " + tgl.after(tgl2));
System.out.println("Selisih tgl dan tgl2 = " +
tgl.compareTo(tgl2));
System.out.println("Apakah tgl = tgl2 ? " + tgl.equals(tgl2));
}
}
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IKG2I4 – Software Project I
RANDOM NUMBER GENERATOR
import java.util.Random;
class CobaRandom {
public static void main(String args[]) {
Random r = new Random();
System.out.println(r.nextInt());
System.out.println(r.nextInt(15000));
System.out.println(r.nextLong());
System.out.println(r.nextDouble());
System.out.println(r.nextFloat());
System.out.println(r.nextBoolean());
}
}
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IKG2I4 – Software Project I
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COLLECTION
Collection adalah struktur data yang sudah
disediakan oleh Java meliputi stack, queue,
linkedlist, vector, dsb.
Ada tiga jenis Collection:
– Ordered List
– Dictionaries
– Set
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IKG2I4 – Software Project I
COLLECTION
Karena array yg biasa kita pakai masih statis, harus
dialokasi size-nya di awal:
– String[] arrString = new String[50]
– Mahasiswa[] arrMhs = new Mahasiswa[50]
Collection adalah penampung (array) yang bersifat
dinamis
– Size-nya bisa mengembang/menyusut otomatis tergantung
pemakaian saat runtime
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IKG2I4 – Software Project I
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COLLECTION: ARRAYLIST
Contoh ArrayList:
ArrayList<String> arrlistMhs = new ArrayList<String>(20);
// initial capacity 20 (bila tidak diisi, defaultnya 10)
arrlistMhs.add("Naruto");
arrlistMhs.add("Sakura");
arrlistMhs.add("Sasuke");
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IKG2I4 – Software Project I
COLLECTION: VECTOR
Contoh Vector:
Vector<String> vectorMhs = new Vector<String>(20);
// initial capacity 20 (bila tidak diisi, defaultnya 10)
vectorMhs.add("Naruto");
vectorMhs.add("Sakura");
vectorMhs.add("Sasuke");
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IKG2I4 – Software Project I
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COLLECTION: LINKEDLIST
Contoh LinkedList:
LinkedList<String> listMhs = new LinkedList<String>();
listMhs.addFirst("1-Naruto");
listMhs.addLast("2-Sakura");
listMhs.addFirst("3-Sasuke");
listMhs.addFirst("4-Doraemon");
listMhs.addLast("5-Nobita");
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IKG2I4 – Software Project I
COLLECTION: STACK
Contoh Stack:
Stack<String> stackMhs = new Stack<String>();
stackMhs.push("1-Naruto");
stackMhs.push("2-Sakura");
stackMhs.push("3-Sasuke");
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IKG2I4 – Software Project I
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COLLECTION: PRIORITYQUEUE
Contoh PriorityQueue:
PriorityQueue<String> queueMhs =
new PriorityQueue<String>();
queueMhs.add("1-Naruto");
queueMhs.add("2-Sakura");
queueMhs.add("3-Sasuke");
queueMhs.add("4-Doraemon");
queueMhs.add("5-Nobita");
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COLLECTION: HASHMAP
Contoh HashMap:
HashMap<Integer,String> hmapMhs =
new HashMap<Integer,String>(20);
// initial capacity 20 (bila tidak diisi, defaultnya 10)
hmapMhs.put(118,"Naruto");
hmapMhs.put(119,"Sakura");
hmapMhs.put(120,"Sasuke");
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COLLECTION: HASHSET
Contoh HashSet:
HashSet<String> hsetMhs = new HashSet<String>(20);
// initial capacity 20 (bila tidak diisi, defaultnya 10)
hsetMhs.add("Naruto");
hsetMhs.add("Sakura");
hsetMhs.add("Sasuke");
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IKG2I4 – Software Project I
JAVA IO STREAM & FILE IO
Java menyediakan cara muda untuk:
– Menampilkan (OUTPUT) sesuatu ke layar
Java menyediakan banyak cara untuk:
– Menerima masukan (INPUT) dari keyboard
– Membaca file (READ)
– Menulis file (WRITE)
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IKG2I4 – Software Project I
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JAVA IO STREAM
import java.util.Scanner; //utility
class Driver {
public static void main(String[] args) {
Scanner objScanner = new Scanner(System.in);
String nama,alamat;
int umur;
float x;
System.out.print("Anjeun saha namina? ");
nama = objScanner.nextLine(); // meminta masukan dari keyboard
System.out.print("Umur berapa? ");
umur = objScanner.nextInt(); // meminta masukan dari keyboard
System.out.print("Masukkan angka float ");
x = objScanner.nextFloat(); // meminta masukan dari keyboard
System.out.println("Halo "+nama);
System.out.println("Umur "+umur+" tahun!");
System.out.println("Angka yang Anda masukkan = "+x);
}
}
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JAVA IO STREAM
System.out.print("Masukkan angka float ");
x = objScanner.nextFloat(); // meminta masukan dari keyboard
System.out.println("Halo "+nama);
System.out.println("Umur "+umur+" tahun!");
System.out.println("Angka yang Anda masukkan = "+x);
}
}
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FILE IO: READ
import java.io.BufferedReader; //paket io untuk BufferedReader
import java.io.InputStreamReader; //paket io untuk InpuStreamReader
import java.io.EOFException;
import java.io.IOException;
import java.io.FileNotFoundException;
class Driver {
public static void main(String[] args) {
try {
FileReader fr = new FileReader("bacajava.txt");
BufferedReader br = new BufferedReader(fr);
String baca;
while((baca=br.readLine())!=null){
//String baca = br.readLine();
System.out.println(baca);
}
br.close();
} catch (FileNotFoundException fnfe) {
} catch (IOException ioe) {
}
}
}
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IKG2I4 – Software Project I
FILE IO: READ
class Driver {
public static void main(String[] args) {
try
{
byte[] arrByte = new byte[10];
FileInputStream fis = new FileInputStream("bacajava.txt");
fis.read(arrByte,0,10);
String baca = new String(arrByte);
System.out.println(baca);
} catch (IOException ioe)
{
}
}
}
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IKG2I4 – Software Project I
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FILE IO: WRITE
class Driver {
public static void main(String[] args) {
try
{
// ciptakan dulu filenya secara fisik
FileOutputStream fos = new FileOutputStream("tulisjava.txt");
byte[] arrByte = “Latihan menulis ke file".getBytes();
fos.write(arrByte);
}
catch (FileNotFoundException fnfe)
{
} catch (IOException ioe)
{
}
}
}
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FILE IO: WRITE
class Driver {
public static void main(String[] args) {
try {
FileOutputStream fos = new
FileOutputStream("tulisjava.txt");
BufferedOutputStream bos = new
BufferedOutputStream(fos);
byte[] arrByte = "Mau nulis ke file nih".getBytes();
bos.write(arrByte);
bos.close();
} catch (FileNotFoundException fnfe) {
} catch (IOException ioe) {
}
}
}
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FILE IO: WRITE
class Driver {
public static void main(String[] args) {
try {
FileOutputStream fos = new FileOutputStream("tulisjava.txt");
PrintWriter pw = new PrintWriter(fos);
pw.println("Practice makes perfect!");
pw.println("No pain no gain!");
pw.println("Berdoa dan berusaha!");
pw.println("Fight for your dream and make it true!");
pw.close();
} catch (FileNotFoundException fnfe) {
} catch (IOException ioe){
}
}
}
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Tugas Minggu ini
Input pakai keyboard Biodata
Data tersebut disimpan ke File text
File dibuka dan dicetak ke layar
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